The present invention relates to grinding machines having a cylindrical grinding wheel mounted on a vertical shaft extending through a horizontal work surface. More particularly, the present invention relates to such grinding machines having an improved work table and grinding wheel.
Grinding machines of the type of this invention primarily used for shaping pieces of stained glass for making glass windows although work pieces of other materials can also be ground to shape using such machines. Work pieces typically ground to shape include ones of glass, ceramic tile, stone, marble, fiberglass and plastic materials. In use, the work piece to be ground is placed on the work table and manually applied to the grinding wheel which is rotated by means of an electric motor. Power to the motor is switched on and off during periods of use and non-use of the machine by means of hand or foot operated switches. While these switches are functional, they sometimes distract one's eyes from the work piece and it would be desirable to have a more convenient and efficient means for activating and deactivating the motor.
It is often necessary to change the grinding wheel, for example, to one having a different abrasive grit or abrasive characteristic or to replace a wheel which has worn out. Grinding wheels are generally coaxially mounted on a vertical shaft driven by the electric motor and secured in place by means of a set screw. Replacement of the wheel simply involves loosening of the set screw, removing the old wheel, mounting the new wheel and then tightening the set screw on the new wheel. This procedure, while straight forward, is sometimes difficult or unpleasant because of ground glass or other material and coolant in the area of the set screw. Thus, it would be desirable to have a grinding wheel assembly which facilitates changing grinding wheels.
The grinding machines are used to grind work pieces having a wide variety of shapes and sizes. For most commonly used sizes of work pieces a regular sized work table is sufficiently large to support the work piece. However, for large work pieces it would be desirable if an oversized work table were available to be substituted for the regular work table.
Having the above points in mind, we have invented a new and improved grinding apparatus. Accordingly, the apparatus of the present invention has a touch-top work table which enables an operator to turn on the motor by applying slight downward force pressure on the table and to turn off the motor by not applying the downward force. The work table of the present invention can be easily interchanged with a larger work table. Furthermore, the grinding wheel device of the present invention facilitates removal of old wheels and installation of new wheels without he necessity of manipulating set screws.
Further understanding of the present invention will be had from the following detailed description and claims taken in conjunction with the accompanying drawings.